| Convergent Tech Events Ltd | Administrative & support | 2025 |
| Conversation Over Borders CIC | Education | 2021 |
| Cook Chick Design Limited | Professional & scientific | 2007 |
| Cook Communications Limited | Other services | 2001 |
| Cool Bloo Ltd | Real estate | 2022 |
| Cool Mask UK Limited | Wholesale & retail | 2020 |
| Coole Bevis LLP | | 2008 |
| Coolfit Conversions Limited | Construction | 1999 |
| Coolgarif Technologies Ltd | Information & communication | 2012 |
| Coolstays Ltd | Information & communication | 2011 |
| Coom Ltd | Real estate | 2021 |
| Coombe LEA Grand Avenue Limited | Households | 1994 |
| Coombe TAN Ltd | Other services | 2022 |
| COOMBE23 Ltd | Construction | 2016 |
| Coombs (Canterbury) Limited | Construction | 1986 |
| Coombs Holdings Limited | Financial services | 2005 |
| Cooper & Cask Limited | Administrative & support | 2026 |
| Cooper Consultancy Limited | Financial services | 1995 |
| Cooper Joinery & CNC Services Limited | Manufacturing | 2018 |
| Cooper Marketing Ltd | Wholesale & retail | 2021 |
| Coppelian Bidco 1 Limited | Financial services | 2022 |
| Coppelian Capital Advisors Limited | Financial services | 2022 |
| Copper Colour Collective Ltd | Other services | 2021 |
| Coppergate Locking Solutions Limited | Professional & scientific | 2021 |
| Coppers Brook Group Limited | Professional & scientific | 2025 |
| Copycat Pearl Holdings LLP | | 2022 |
| Copycat Pearl Limited | Mining & quarrying | 2022 |
| Copytech Limited | Manufacturing | 1994 |
| Coralcutinholtd Limited | Health & social care | 2025 |
| Corbarrow Ltd | Financial services | 2024 |
| Corder Carpentry Services Ltd | Manufacturing | 2021 |
| Core Guitars Ltd | Manufacturing | 2018 |
| Core SME Limited | Education | 2010 |
| Core Works Ltd | Wholesale & retail | 2023 |
| Corke Wallis Ltd | Professional & scientific | 2010 |
| Corley Creative Ltd | Arts & recreation | 2023 |
| Corner Nest Ltd | Wholesale & retail | 2026 |
| Cornfield Law LLP | | 2003 |
| Cornwall House Brighton Limited | Households | 2003 |
| Cornwall Properties U K Ltd | Households | 2025 |
| Corporate Business Strategies Limited | Professional & scientific | 2014 |
| Corporations Capital Limited | Manufacturing | 2025 |
| Corr Products Limited | Wholesale & retail | 2026 |
| Corrado Consulting Ltd | Professional & scientific | 2020 |
| Corridor Projects CIC | Education | 2020 |
| Corsair Films Limited | Information & communication | 2004 |
| Corsair Finance Ltd | Professional & scientific | 2015 |
| Corstorphine Dental Centre Limited | Health & social care | 2015 |
| Cortex International Ltd | Professional & scientific | 2023 |
| Cortex IT Ltd | Information & communication | 2007 |
| Cortongrade Properties Limited | Construction | 2001 |
| Cortébert Limited | Extraterritorial | 2022 |
| Corvus Construction Inc Ltd | Construction | 2023 |
| Cosaris Ltd | Professional & scientific | 2014 |
| Cosmic Circles Ltd | Financial services | 2022 |
| Cosmic Fish Limited | Information & communication | 2014 |
| Cosmos Creative Ltd | Wholesale & retail | 2022 |
| Cosy Cottage Cafe Bar Ltd | Hospitality | 2022 |
| Cosyfeat Limited | Hospitality | 2012 |
| Cotswold Rooms Limited | Hospitality | 2017 |
| Cotswolds Catering Ltd | Hospitality | 2022 |
| Coucoumella Ltd | Professional & scientific | 2025 |
| Couldbeworse Ltd | Wholesale & retail | 2025 |
| Coulter Investments Ltd | Real estate | 2019 |
| Counselling & Psychotherapy Ltd | Education | 2025 |
| Counselling Psych Limited | Health & social care | 2016 |
| Counter Risk Consultancy Ltd | Administrative & support | 2019 |
| Counterpart Studio Ltd | Professional & scientific | 2021 |
| Country Beagles Ltd | Real estate | 2025 |
| County Cash Registers Limited | Professional & scientific | 1979 |
| County Oak News Limited | Transport & logistics | 2010 |
| County Structures Ltd | Construction | 2022 |
| Coup DE Coeur London Limited | Administrative & support | 2016 |
| Courage LAB Ltd | Other services | 2022 |
| Courcels RTM Company Limited | Households | 2022 |
| Cournoyer Healthcare Limited | Manufacturing | 2025 |
| Court Farm Car Sales Limited | Wholesale & retail | 1979 |
| Courtenay Lodge Management Company Limited | Households | 1981 |
| Courtney Smith & Co. Ltd. | Administrative & support | 1987 |
| Cove Communications Consultancy Ltd | Professional & scientific | 2023 |
| Cove Communities Holiday Park UK Holdco Limited | Real estate | 2021 |
| Cove Communities Venture 2 Gwel an MOR Opco Limited | Hospitality | 1990 |
| Cove Communities Venture 2 Solway Opco Limited | Real estate | 2022 |
| Cove Communities Venture 2 Springwood Opco Limited | Real estate | 2022 |
| Cove Consulting LLP | | 2024 |
| Cove Consulting Services Limited | Administrative & support | 2025 |
| Cove Healthcare Limited | Health & social care | 2020 |
| Cover-Belles Ltd | Other services | 2025 |
| COW Corner 1 GP LLP | | 2020 |
| COW Corner 1 LP | | 2020 |
| COW Corner 2 LP | | 2023 |
| COW Corner 3 LP | | 2025 |
| COW Corner Accounting 1 Limited | Financial services | 2021 |
| COW Corner F2 (NO. 1) Limited | Financial services | 2023 |
| COW Corner Finance Limited | Financial services | 2018 |
| COW Corner Group Limited | Financial services | 2018 |
| COW Corner Holdings Limited | Financial services | 2018 |
| COW Corner Investing Ltd | Financial services | 2020 |
| COW Corner Investments (NO 5) Limited | Financial services | 2022 |
| COW Corner Investments (NO. 7) Limited | Financial services | 2024 |